Life Sciences Commons^™

Rapid Source To Sink Transition In A Mixed-Conifer Forest Following Stand-Replacing Fire, Ryan Matthew Schulze

Biology ETDs

Mixed-conifer forests play an important role in the Southwestern USA’s regional carbon cycle by sequestering and storing large amounts of atmospheric carbon onto the landscape. Despite this, little is known about how large, stand-replacing fire alters ecosystem carbon sink-source dynamics. In this study, we used eddy covariance to quantify how stand-replacing fire altered forest sink strength, and the sensitivity of carbon uptake to soil and atmospheric drought in a mixed-conifer forest located in The Valles Caldera National Preserve, NM. We found that the post-burn ecosystem returned to an annual net sink of carbon in the year immediately following the fire, …

Sex- And Age - Specific Migratory Strategies Of Blue Whales In The Northeast Pacific, Christina Blevins

Biology ETDs

Sequential subsampling of blue whale baleen plates can yield information of individual migratory plasticity of this endangered species in the northeast Pacific Ocean. We measured δ13C and δ15N isotope values along baleen from thirteen whales of different age and sex. Results showed sex/age-specific migratory strategies. Adult females exhibited relatively stable cyclical movements between temperate and subtropical regions. Adult males exhibited two strategies, most remained within temperate latitudes, whereas two migrated to subtropical latitudes. Movement patterns in juveniles were erratic. These patterns are potentially driven by energetic requirements of females, intraspecific competitions among adult males, and inexperience in locating prey in …

Comparative Phylogeography Across Multiple Scales: Small Mammals, Their Ecology, Pathogens, And Drivers Of Diversification, Schuyler W. Liphardt

Biology ETDs

Comparative phylogeography has historically been defined as the study of how genetic variation of co-distributed species has been shaped by biogeographical history. This is a mature field of study out of which several techniques have been developed directed at identifying the role ecology and geography in diversification patterns across time. I employ the tools developed in classical comparative phylogeography across multiple taxonomic scales and across regions that historically have been understudied. My first two chapters study the complex history of host-switching, codiversification, and reassortment of hantaviruses in their mammal hosts across North America. By taking a host-centric comparative phylogeographic approach …

Quantification Of Soil Microbial Biomass In The Mcmurdo Dry Valleys, Antarctica, Emily Ruth Reynebeau

Biology ETDs

Quantifying microbial biomass is important for understanding microbial contribution to

nutrient cycling and population flux. Widely accepted biomass estimation methods are

sufficient for well-studied and high biomass systems, though are often not sensitive enough

for systems with extremely low biomass. The McMurdo Dry Valleys of Antarctica are

characterized as an extremely harsh environment with severe restrictions on life, with

perhaps some of the lowest biomass in the world. We measured prokaryote biomass across

Taylor and Wright Valleys using four estimation metrics to determine the most appropriate

method for this ecosystem. The chloroform fumigation method was not sensitive enough

for the …

Breathing Can Be Dangerous: Coccidioides And The Diverse Community Of The Lung Mycobiome, Paris Salazar-Hamm

Biology ETDs

Coccidioidomycosis, caused by soil-dwelling species of Coccidioides, is endemic to the Southwestern United States. It can present as a mild respiratory illness to life-threatening disseminated infections.Multi-gene phylogenetics and tracing patient histories revealed the presence of both Coccidioides species in New Mexico, and Native Americans may represent an unrecognized risk group. A PCR method developed distinguishes Coccidioides species by targeting regions of the mitochondrial genome. Recent advancements in molecular genetics solidifies lungs are not sterile. Illumina community data from 199 small mammals from Arizona, California, and New Mexico demonstrated a great diversity of fungi inhabiting lung tissues. One dominant order, Onygenales, …

Global Population Divergence Of A Cosmopolian Desert Plant, Victor Ryan Alfaro

Biology ETDs

Genetic and phenotypic variation can have different patterns within a species if it has populations with contrasting histories. Populations can have discrete differences that are shaped by different evolutionary scenarios, but within each population, range, or region, traits and association with fitness can also be affected by both edaphic and landscape variation. For my dissertation, I surveyed and experimentally analyzed variation and adaptive potential in Sahara mustard (Brassica tournefortii), a desert annual that has endemic, invasive, and agricultural populations in Africa, Asia, and the Americas. Although my multi-trait analysis generated complex results, my findings can be applied to …

Mud Binds Mitotic Kinesins Non-Claret Disjunctional And Pavarotti In D. Melanogaster, Vincent Cutillas

Biology ETDs

The cytoskeleton is crucial to maintaining an even distribution of chromosomes and subsequently to divide the cell during every cell cycle. During mitosis, spindle structure and movement dictates how chromosomes will be separated and act as the sole mechanism for even distribution of these chromosomes. The cytoskeleton also remains a major cellular component during cytokinesis when the cell must cleave the membrane in order to form two resulting daughter cells. Both processes require an extensive use of the immobile structures of the cytoskeleton, such as microtubules (MTs), intermediate filaments, and microfilaments, but also the mobile units, which are the motor …

The Role Of Toxoplasma Gondii Dense Granule Protein Gra24 In Signaling And Immunity During Infection, Heather L. Mercer

Biology ETDs

Toxoplasma gondii is a pathogen whose control partly depends upon Toll-like receptors (TLR) 11 and 12, that signal through MyD88. Yet, human TLR11 and TLR12 are nonfunctional, motivating us to investigate MyD88-independent immune pathways. Parasite dense granule protein GRA24 activates p38 MAPK independently of MyD88 in macrophages. Using wild-type and GRA24-deleted T. gondii strains, I demonstrate GRA24 activates p38 MAPK, resulting in IL-12 production, and protective immunity. Furthermore, GRA24 triggers p38 MAPK-dependent CX3CL1 production. GRA24 also induces CCL17 and Ppbp independently of p38 MAPK. Additionally, I demonstrate GRA24 downregulates CCL12. Furthermore, IL-15 is negatively regulated by GRA24 through activation …

What Does The Future Look Like? Plant Community Change At The Recruitment Life Stage, Brooke E. Wainwright

Biology ETDs

Species ranges are shifting due to anthropogenic climate change. However, it is unclear how climate variability affects species recruitment, an essential step in range expansion. Recruitment is challenging in drylands, where soil moisture is highly unpredictable. In Southwestern North America, creosotebush (Larrea tridentata) has expanded into Chihuahuan Desert grassland (CDG) dominated by black grama (Bouteloua eriopoda), and black grama is expanding into Great Plains grassland (GPG) dominated by blue grama (Bouteloua gracilis). To evaluate how precipitation variability affects germination and survivorship, we added blue and black grama seeds into a climate variability experiment in GPG in 2019 and 2020 and …

Into The Neotropics: Perspectives On The Evolution Of Neotropical Myotis, Carlos Alberto Carrion Mr

Biology ETDs

In my dissertation, I used morphological, sanger sequencing and next-generation sequencing data sets to explore the evolutionary relationships and study cryptic diversity of a extant Neotropical myotine radiation. Using a integrative approach, I described a new species of Myotis from the montane and premontane forest of Panama, Costa Rica and Eastern Ecuador, refining our undestanding of the taxonomy and systematics of the Myotis pilosatibialis complex of bats. Then, using a single locus barcoding approach I explored genetic diversity partitioning across the Myotis radiation with a focus on Neotropical species, ilustrating the phylogenetic relationships of Neotropical species and exploring their species …

The Impacts Of Disturbance On Submerged Aquatic Macrophytes Populations Of The Jemez Mountains, New Mexico, Virginia F. Thompson

Biology ETDs

This dissertation investigates the effects of disturbance (a catastrophic forest fire and decadal-level multi-day flood) on populations of submerged aquatic macrophytes (SAMs) in the streams and rivers of the Jemez Mountains of northern New Mexico, USA. Research conducted and reported in this dissertation addresses the following research questions: 1.) What factors influence the presence or absence of SAMs in Jemez Mountain streams? 2.) How does disturbance (catastrophic wildfire and decadal-level flood) change the amount of aboveground SAM biomass? and 3.) How does that disturbance change the nutrient content (%C, %N, %P) and nutrient stoichiometry of SAMs? These disturbance events had …

The Phylogeography And Molecular Systematics Of Woodrats (Genus: Neotoma) In The American Southwest, Katrina Derieg

Biology ETDs

The American Southwest is a region where many biomes converge, harboring a wide variety of habitats ranging from desert to alpine environments. Habitat heterogeneity and the confluence of multiple species ranges make the American Southwest a biodiversity hotspot. Climate cycling throughout the Quaternary has driven the dynamics of changes in species’ ranges that are recorded by genetic signatures. For example, range expansion may lead to secondary contact between previously isolated populations or species. Contact can result in multiple evolutionary outcomes, including hybridization or the reinforcement and maintenance of independent lineages. I used multi-locus species tree methods to re-examine the nominal …

Heterogeneity In Hosts And Environment: Implications For Schistosomiasis Control, Larissa C. Anderson

Biology ETDs

Schistosomiasis is a widespread neglected parasitic disease, endemic in 54 countries, for which 290 million people needed treatment in 2018. A major Schistosoma species, Schistosoma mansoni, is sustained via a life cycle that includes both human and snail hosts. Mathematical models of S. mansoni transmission are an integral tool for elucidating the complexities of the transmission cycle, interactions between parasite species and for the estimation of the impact of intervention efforts. We designed both deterministic and stochastic mathematical models to understand the impact of heterogeneity in host and parasite composition on projected infection control. These models indicate the impact of …